decode/icmpv4: switch ptr checks to PKT_IS_ICMPV4

To prepare future changes to the Packet header pointers.

Ticket: #5517.

src/detect-csum.c

@@ -682,7 +682,7 @@ static int DetectICMPV4CsumMatch(DetectEngineThreadCtx *det_ctx,
 {
     const DetectCsumData *cd = (const DetectCsumData *)ctx;
 
-    if (!PacketIsIPv4(p) || p->icmpv4h == NULL || p->proto != IPPROTO_ICMP || PKT_IS_PSEUDOPKT(p))
+    if (!PacketIsIPv4(p) || !PKT_IS_ICMPV4(p) || p->proto != IPPROTO_ICMP || PKT_IS_PSEUDOPKT(p))
         return 0;
 
     if (p->flags & PKT_IGNORE_CHECKSUM) {

src/detect-icmpv4hdr.c

@@ -95,7 +95,7 @@ static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
 {
     SCEnter();
 
-    if (p->icmpv4h == NULL) {
+    if (!PKT_IS_ICMPV4(p)) {
         SCReturnPtr(NULL, "InspectionBuffer");
     }
 

src/flow-util.c

@@ -176,7 +176,7 @@ void FlowInit(Flow *f, const Packet *p)
     } else if (PKT_IS_UDP(p)) {
         SET_UDP_SRC_PORT(p,&f->sp);
         SET_UDP_DST_PORT(p,&f->dp);
-    } else if (p->icmpv4h != NULL) {
+    } else if (PKT_IS_ICMPV4(p)) {
         f->icmp_s.type = p->icmp_s.type;
         f->icmp_s.code = p->icmp_s.code;
         FlowSetICMPv4CounterPart(f);